dse.util - Utilities

Functions

dse.util.

datetime_from_timestamp

(timestamp)

Creates a timezone-agnostic datetime from timestamp (in seconds) in a consistent manner. Works around a Windows issue with large negative timestamps (PYTHON-119), and rounding differences in Python 3.4 (PYTHON-340).

Parameters

timestamp – a unix timestamp, in seconds

dse.util.

utc_datetime_from_ms_timestamp

(timestamp)

Creates a UTC datetime from a timestamp in milliseconds. See datetime_from_timestamp().

Raises an OverflowError if the timestamp is out of range for datetime.

Parameters

timestamp – timestamp, in milliseconds

dse.util.

ms_timestamp_from_datetime

(dt)

Converts a datetime to a timestamp expressed in milliseconds.

Parameters

dt – a datetime.datetime

dse.util.

unix_time_from_uuid1

(uuid_arg)

Converts a version 1 uuid.UUID to a timestamp with the same precision as time.time() returns. This is useful for examining the results of queries returning a v1 UUID.

Parameters

uuid_arg – a version 1 UUID

dse.util.

datetime_from_uuid1

(uuid_arg)

Creates a timezone-agnostic datetime from the timestamp in the specified type-1 UUID.

Parameters

uuid_arg – a version 1 UUID

dse.util.

min_uuid_from_time

(timestamp)

Generates the minimum TimeUUID (type 1) for a given timestamp, as compared by Cassandra.

See uuid_from_time() for argument and return types.

dse.util.

max_uuid_from_time

(timestamp)

Generates the maximum TimeUUID (type 1) for a given timestamp, as compared by Cassandra.

See uuid_from_time() for argument and return types.

dse.util.

uuid_from_time

(time_arg, node=None, clock_seq=None)

Converts a datetime or timestamp to a type 1 uuid.UUID.

Parameters

  • time_arg – The time to use for the timestamp portion of the UUID. This can either be a datetime object or a timestamp in seconds (as returned from time.time()).

  • node (long) – None integer for the UUID (up to 48 bits). If not specified, this field is randomized.

  • clock_seq (int) – Clock sequence field for the UUID (up to 14 bits). If not specified, a random sequence is generated.

Return type

uuid.UUID

Module Data

dse.util.

LOWEST_TIME_UUID

= UUID(‘00000000-0000-1000-8080-808080808080’)

The lowest possible TimeUUID, as sorted by Cassandra.

dse.util.

HIGHEST_TIME_UUID

= UUID(‘ffffffff-ffff-1fff-bf7f-7f7f7f7f7f7f’)

The highest possible TimeUUID, as sorted by Cassandra.

class SortedSet

A sorted set based on sorted list

A sorted set implementation is used in this case because it does not require its elements to be immutable/hashable.

#Not implemented: update functions, inplace operators

Attributes

dse.util.

sortedset

alias of dse.util.SortedSet

class OrderedMap

An ordered map that accepts non-hashable types for keys. It also maintains the insertion order of items, behaving as OrderedDict in that regard. These maps are constructed and read just as normal mapping types, exept that they may contain arbitrary collections and other non-hashable items as keys:

>>> od = OrderedMap([({'one': 1, 'two': 2}, 'value'),
...                  ({'three': 3, 'four': 4}, 'value2')])
>>> list(od.keys())
[{'two': 2, 'one': 1}, {'three': 3, 'four': 4}]
>>> list(od.values())
['value', 'value2']

These constructs are needed to support nested collections in Cassandra 2.1.3+, where frozen collections can be specified as parameters to others:

CREATE TABLE example (
    ...
    value map<frozen<map<int, int>>, double>
    ...
)

This class derives from the (immutable) Mapping API. Objects in these maps are not intended be modified.

class OrderedMapSerializedKey

class Time

Idealized time, independent of day.

Up to nanosecond resolution

Initializer value can be:

  • integer_type: absolute nanoseconds in the day

  • datetime.time: built-in time

  • string_type: a string time of the form “HH:MM:SS[.mmmuuunnn]”

Attributes

hour

The hour component of this time (0-23)

minute

The minute component of this time (0-59)

second

The second component of this time (0-59)

nanosecond

The fractional seconds component of the time, in nanoseconds

Methods

time

()

Return a built-in datetime.time (nanosecond precision truncated to micros).

class Date

Idealized date: year, month, day

Offers wider year range than datetime.date. For Dates that cannot be represented as a datetime.date (because datetime.MINYEAR, datetime.MAXYEAR), this type falls back to printing days_from_epoch offset.

Initializer value can be:

  • integer_type: absolute days from epoch (1970, 1, 1). Can be negative.

  • datetime.date: built-in date

  • string_type: a string time of the form “yyyy-mm-dd”

Attributes

seconds

Absolute seconds from epoch (can be negative)

Methods

date

()

Return a built-in datetime.date for Dates falling in the years [datetime.MINYEAR, datetime.MAXYEAR]

ValueError is raised for Dates outside this range.

Functions

dse.util.

inet_ntop

(af, packed_ip)string formatted IP address

Windows doesn’t have socket.inet_pton and socket.inet_ntop until Python 3.4 This is an alternative impl using ctypes, based on this win_inet_pton project: https://github.com/hickeroar/win_inet_pton

class Point

Represents a point geometry for DSE

Attributes

x

= None

x coordinate of the point

y

= None

y coordinate of the point

Static Methods

static

from_wkt

(s)

Parse a Point geometry from a wkt string and return a new Point object.

class LineString

Represents a linestring geometry for DSE

‘coords`: a sequence of (x, y) coordinates of points in the linestring

Attributes

coords

= None

Tuple of (x, y) coordinates in the linestring

Static Methods

static

from_wkt

(s)

Parse a LineString geometry from a wkt string and return a new LineString object.

class Polygon

Represents a polygon geometry for DSE

‘exterior`: a sequence of (x, y) coordinates of points in the linestring interiors: None, or a sequence of sequences or (x, y) coordinates of points describing interior linear rings

Attributes

exterior

= None

_LinearRing representing the exterior of the polygon

interiors

= None

Tuple of _LinearRings representing interior holes in the polygon

Static Methods

static

from_wkt

(s)

Parse a Polygon geometry from a wkt string and return a new Polygon object.

class Distance

Represents a Distance geometry for DSE

Attributes

x

= None

x coordinate of the center point

y

= None

y coordinate of the center point

radius

= None

radius to represent the distance from the center point

Static Methods

static

from_wkt

(s)

Parse a Distance geometry from a wkt string and return a new Distance object.

class Duration

Cassandra Duration Type

class DateRangePrecision

An “enum” representing the valid values for DateRange.precision.

Attributes

YEAR

= ‘YEAR’

MONTH

= ‘MONTH’

DAY

= ‘DAY’

HOUR

= ‘HOUR’

MINUTE

= ‘MINUTE’

SECOND

= ‘SECOND’

MILLISECOND

= ‘MILLISECOND’

PRECISIONS

= (‘YEAR’, ‘MONTH’, ‘DAY’, ‘HOUR’, ‘MINUTE’, ‘SECOND’, ‘MILLISECOND’)

class DateRangeBound

Represents a single date value and its precision for DateRange.

Attributes

milliseconds

Integer representing milliseconds since the UNIX epoch. May be negative.

precision

String representing the precision of a bound. Must be a valid DateRangePrecision member.

DateRangeBound uses a millisecond offset from the UNIX epoch to allow DateRange to represent values datetime.datetime cannot. For such values, string representions will show this offset rather than the CQL representation.

Parameters

  • value – a value representing ms since the epoch. Accepts an integer or a datetime.

  • precision – a string representing precision

Methods

datetime

()

Return milliseconds as a datetime.datetime if possible. Raises an OverflowError if the value is out of range.

Class Methods

classmethod

from_value

(value)

Construct a new DateRangeBound from a given value. If possible, use the value[‘milliseconds’] and value[‘precision’] keys of the argument. Otherwise, use the argument as a (milliseconds, precision) iterable.

Parameters

value – a dictlike or iterable object

Module Data

dse.util.

OPEN_BOUND

= DateRangeBound(milliseconds=None, precision=None)

Represents *, an open value or bound for DateRange.

class DateRange

DSE DateRange Type

Attributes

lower_bound

DateRangeBound representing the lower bound of a bounded range.

upper_bound

DateRangeBound representing the upper bound of a bounded range.

value

DateRangeBound representing the value of a single-value range.

As noted in its documentation, DateRangeBound uses a millisecond offset from the UNIX epoch to allow DateRange to represent values datetime.datetime cannot. For such values, string representions will show this offset rather than the CQL representation.

Parameters

class Version

Internal minimalist class to compare versions. A valid version is: <int>.<int>.<int>.<int or str>.

TODO: when python2 support is removed, use packaging.version.